The invention relates to rotary internal combustion engines of the type disclosed in U.S. Pat. No. 2,988,065 granted June 13, 1961 to Wankel et al.
In engines of this type, the engine working chambers rotate with the engine rotor and as a result unburnt fuel tends to accumulate in each working chamber adjacent the trailing end of the chamber from which it is discharged into the engine exhaust port. This problem has been recognized in U.S. Pat. No. 3,393,666 granted July 23, 1968 to Yamamoto et al.
In said prior U.S. Pat. No. 3,393,666, one or more grooves are provided in the inner trochoid surface of the rotor housing in the region in which combustion takes place so that when a rotor apex seal passes over the grooves, the pressure differential across the apex seal blows any unburnt fuel into the following working chamber (that is, into the working chamber on the trailing side of said apex seal) for subsequent combustion therein. In U.S. Pat. No. 3,393,666, however, the grooves in the trochoid surface have such length and are so positioned that when an apex seal of the rotor starts across the grooves, the following working chamber (that is, the chamber on the trailing side of said seal) is still open to the engine intake port and before said apex seal passes completely across the grooves, the working chamber on the leading side of the seal opens to the exhaust port. This has several disadvantages. First, any leakage through the grooves into the following working chamber while said following chamber is still open to the intake port will tend to reduce the amount of fresh charge taken into that chamber. In addition, if the working chamber on the leading side of an apex seal opens to an exhaust port before the seal travels completely across the trochoid grooves, then the pressure differential across the seal probably will reverse before the seal is completely across the grooves whereupon there will be a pressure loss from the following chamber into the leading chamber.